Unstacking machine for trays and the like

ABSTRACT

An unstacking machine for trays and the like disposed in elevationally stacked relation providing a frame adapted to receive such a stack of trays including powered tray pick-off means mounted on the frame for reciprocal movement successively to engage the uppermost tray in the stack and to remove it laterally substantially horizontally from the stack and powered stack elevating means on the frame operative upwardly to advance the stack through successive increments of travel to position each succeeding uppermost tray in the path of movement of said pick-off means for removing the trays one at a time from the stack.

United States Patent Garabedian et al.

[54] UNSTACKING MACHINE FOR TRAYS AND THE LIKE Inventors: Joseph Garabedian, 737 West Yale Avenue; Mike Garabedian, v341 South Maple, both of Fresno, Calif.

Filed: June 23', 1971 Appl. No.: 155,944

US. Cl. ..2l4/8.5 A, 214/85 F Int. Cl ..B65g 59/02 Field of Search ..214/8.5 F, 8.5 A, 8.5 R

[56] References Cited UNITED STATES PATENTS /1963 Bechtold .214/8.5

Verrinder ..2l4/8 5 A [11] 3,722,713 [4 1 Mar. 27, 1973 FOREIGN PATENTS OR APPLICATIONS 1,013 2/1963 Japan ..2l4/8.5A 233,468 8/1962 Austria ..2l4/8.5F

Primary Examiner-Robert G. Sheridan Assistant Examiner-George F. Abraham Attorney-Huebner & Worrel [57] ABSTRACT An unstacking machine for trays and the like disposed in elevationally stacked relation providing a frame adaptedto receive such a stack of trays including powered tray pick-off means mounted on the frame for reciprocal movement successively to engage the uppermost tray in the stack and to remove it laterally substantially horizontally from the stack and powered stack elevating means on the frame operative upwardly to advance the stack through successive increments of travel to position each succeeding uppermost tray in the path of movement of said pick-off means for removing the trays one at a time from the stack.

16 Claims, 9 Drawing Figures 1 rum PATEHTFUHARZYISB 3,722,713

JOSEPH GARABEOMN MIKE GARABED/AN INVENTORS Mw/M A TTORNEYS PATEIHEBHARZYIEB 3,722,713

SHEET 2 BF 5 JOSEPH GAR/1 8E DIAN M/KE GA RABED/AN IN VE N 7095 ATTORNEYS PATENTEUHARZTIQYS SHEET 3 BF 5 3 a a K R N W M M G H P E w J MIKE GARABED/AN INVENTORS ,4 TTORNFVS UNSTACKING MACHINE FOR TRAYS AND THE LIKE BACKGROUND OF THE INVENTION I fruit thereon. After the drying operation is completed,

the stacks of trays are transferred from the drying area to a cleaning station usually on small railroad type cars. The trays are thereupon unstacked by hand and placed upon a conveyor having a tray dumping mechanism associated therewith for removing the fruit from the trays. The fruit is then carried by the conveyor into subsequent cleaning and grading stations for further processing. The hand labor involved in unstacking the trays and loading them onto the fruit processing conveyor is an arduous task requiring the continuous efforts of at least two men, which task the present invention is intended to replace.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved unstacking machine for a plurality of elevationally stacked trays or the like.

Another object is to provide such an improved unstacking machine which is substantially automatic, requiring a minimum of manual attention.

Another object is to provide an improved unstacking machine of the character described which substantially eliminates all manual handling of the trays.

Another object is to provide an improved unstacking machine which is effective automatically to unstack a plurality of trays and load them one at a time onto an elevated conveyor.

Another object is to provide an improved unstacking machine having a frame adapted readily to receive therein an entire stack of trays or the like and to elevate such stack of trays during lateral removal of one tray at a time from the top of the stack.

Another object is to provide an improved unstacking machine which utilizes a tray pick-off mechanism at the top of tray elevating conveyors for movement of the stack upwardly through successive increments of travel to position each succeeding uppermost tray in operational relation to the pick-off mechanism.

Another object is to provide an improved unstacking machine which employs a tray separating mechanism to insure that only one tray at a time is removed from the stack in a relatively smooth, unhampered mariner.

Other objects and advantages of the present invention will subsequently become more clearly apparent upon reference to the following description and accom panying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS 'FIG. I is a front elevation of an unstacking machine for raisin trays or the like embodying the principles of the present invention.

FIG. 2 is a rear elevation of the unstacking machine of FIG. 1.

FIG. 3 is an end elevation of the unstacking machine, as viewed from the right-hand end in FIG. 1.

, at the back side FIG. 4 is a transverse vertical section through the un- FIG. 1.

FIG. 5 is a somewhat enlarged transverse vertical section through the unstacking machine, taken on line 55 of FIG. 4.

FIG.'6 is a somewhat enlarged transverse horizontal section through the unstacking machine, taken on line 6-6 of FIG. 5.

FIG. 7 is a somewhat enlarged transverse vertical section through the unstacking machine, taken on line 7-7 of FIG. 2.

FIG. 8 is a somewhat enlarged transverse vertical section through the unstacking machine, taken on line 88 of H07.

FIG. 9 is a somewhat enlarged fragmentary top plan view of one end of the unstacking machine of the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, an unstacking machine embodying the principles of the present invention has a substantially rectangular upright frame 10 adapted to be rested upon a support surface, such as a floor 11. The frame is further adapted to be disposed in straddling relation to a track 12 having a pair of spaced, substantially parallel rails 14 imbedded within the floor 11. A relatively small railway car 16 provides a flat bed 17 which is rollably supported on the rails by a plurality of wheels 18. A plurality of raisin trays or the like which are indicated in dashed lines and by the reference numeral 20, are disposed upon the flat bed of the railway car in elevationally stacked relation. It is apparent, however, that the trays may be delivered to the unstacking machine of the present invention in any desired manner such as by a forklift truck or the like.

The frame 10 of the unstacking machine of the present invention provides a relatively open front side 22, an opposite back side 23, opposite top and bottom sides 25 and 26, respectively, and opposite ends 27 and 28, as viewed from left to right in FIG. 1. The frame is constructed of a plurality of spaced substantially upright parallel corner posts 30 with the posts at the front and back sides of the frame being interconnected at their upper ends adjacent to the top side of the frame by an elongated connector beam 32. The corner posts 23 of the frame are further strengthened by a lower connector beam 34 and an upwardly spaced intermediate beam 35. The beams are rigidly secured at their opposite ends to their respective corner posts in any suitable manner such as by bolting, welding or the like.

A- pair of elevationally spaced angle iron braces 37 are disposed in interconnecting relation between the frame in precisely centered position. Each of the rollers is mounted on an elongated shaft 42 having ends journaled in bearings 43 mounted on brackets 45 secured to the adjacent corner post 30 of the frame. v

At each end 27 and 28 of the frame is provided an elongated stack elevating conveyor, generally indicated by the reference numeral 50. Each conveyor provides a pair of laterally spaced, substantially parallel endless chains 52 individually providing'an inner run 53 and an opposite outer run 54 and being trained for circuitous movement about a pair of opposite upper and lower sprockets 57 and 58, respectively. The two upper sprockets S7 at each end of the frame, as best shown in FIG. 4, are individually mounted on theinner end of a stub shaft 60 which is rotatably supported adjacent to the sprocket by extension through a bearing and pillow block assembly 62. The assembly is supported on an angle bracket 63 secured to the inner surface of the upper end of the associated corner post 30. The outer end of the stub shaft 60 is extended through an outer support bearing and pillow block assembly 65 mounted on an angle iron bracket 66 secured to the outer surface of the corner post. A drive transfer sprocket 68 is mounted on the outer end of the shaft for a purpose subsequently to be described.

The lower sprockets 58 of the stack elevating conveyor 50 are mounted in a substantially similar manner to the upper sprockets 57. Each of the lower sprockets at each end of the frame 10 is mounted on a stub shaft 70 which is extended through a pair of inner and outer bearing and pillow block assemblies 72 and 73, respectively. Such assemblies are supported in depending relation from a pair of associated inner and outer angle iron brackets 74 and 75 secured to the adjacent sides of the-corner posts 30.

At the end 28 the end of the frame 10 a relatively large diameter sprocket 84, as best shown in FIG. 9, which is approximately twice the size of the drive transfer sprockets 68, is disposed on each of the stub shafts 60 between its associated drive transfer sprocket and pillow block and bearing assembly 65. A pair of elongated endless chains 87 and 88 are disposed at the front and back sides 22 and 23 of the frame 10, respectively, for circuitous movement about the drive transfer sprockets 68 at the opposite ends of the frame 10 with their intermediate run portions being crossed in order to travel the inner runs 53 of all the chains 52 in an upward direction.

As best shown in FIGS. 2 and 3, the conveyors are driven from an hydraulic motor 90 mounted on a bracket 92 secured to the adjacent corner post at the back side 23 of the frame. The motor includes a drive shaft 94 which mounts a drive sprocket 95 having a drive chain 96 trained about it and a relatively large diameter sprocket 98. The large sprocket is mounted on a cross shaft 100 which is journaled in a pair of spaced bearing and pillow block assemblies 102 individually supported on extensions of their adjacent angle iron brackets 66. A reduced diameter sprocket 104 is mounted inwardly adjacent to the large sprocket on the cross shaft in coplanar relation with the large diameter sprocket 84 on the adjacent stub shaft 60. A drive chain 105 is trained about the small sprocket 104 and the large diameter sprocket 84 to transmit the power to the stack elevating conveyors 50. A similar sprocket and chain drive assembly is disposed at the front side 22 of the frame and identical reference numerals have been supplied to the corresponding elements.

A pair of stack receiving flight members are mounted on each of the stack elevating conveyors 50. As best shown in FIGS. 3, 4 and 5, each of the flight members provides an elongated angle iron having a substantially horizontal tray engaging portion 112 and a substantially upstanding mounting portion 114. The angle iron is' secured at its opposite ends to the lower ends of apair of elongated arms 116, the opposite upper ends of which are pivotally mounted on the chains 52 of each conveyor with the angle iron members disposed in transversely spanning relation therebetween. The upper ends are pivotally mounted on pivot bolts 117 inwardly extended from their respective chains and an elongated weight 118 is secured to the back of the mounting portion of the angle iron to insure that the flight members are maintained in depending relation from the chains during the above described circuitous movement of the chains between the upper and lower sprockets 57 and 58. The flight members are spaced in opposed relation to each other so that, as best shown in FIG. 5, when one flight member is disposed adjacent to the upper sprocket, the other flight member is located in diametrically opposed relation adjacent to the lower sprocket.

As best shown in FIGS. 5 and 6, the inner runs 53 of the conveyor chains 52 are dependably'guided and maintained in a substantially upright vertical path of travel by a chain guide assembly, generally indicated by the reference numeral 120. The guide assembly includes a pair of upper and lower angle iron support frames 122 having an elongated, substantially horizontal frame member 123 transversely extended between the comer posts 30 which is secured thereto by a pair of opposite right-angularly related mounting arms 124. Each of the arms has an elongated slot 125 through which is extended a mounting bolt and nut assembly 126 to. permit inward and outward adjustment of the guide assembly. A pair of elongated, substantially upright channular beams 127 are individually mounted, as by welding or the like, between the upper and lower frame members inwardly adjacent to the inner run 53 of the chains. Each of the beams has an elongated guide rail 128 secured to the face thereof for sliding engagement against the rollers of the chain with the side link members disposed in slidably embracing relation to the rail. An opposite rail 130 is disposed against the opposite side of the chain in a similar manner and is held in such position by an elongated angle iron 132 supported on the outer side of the beam by an elongated mounting plate 135.

The outer run 54 of each of the chains 52 of the stack elevating conveyors 50 is held endwardly outwardly of the frame 10 by a pair of elongated substantially upright guide bars having a substantially straight intermediate portion 142 and angularly related opposite ends 143 secured, as by welding or the like, to the upper and'lower ends of the beams 127. The guide bars are thereby effective to maintain the outer runs of the chains in outwardly spaced relation from the inner runs and the frameby engagement with the roller portions of the chains with the opposite links thereof embracing the sides of the bars to preclude lateral displacement of the chains from their respective guide bars. An elongated flight member camming bar 145 is disposed substantially intermediate the chains upon the guide frame 122 between the angle iron frame members 123 thereof which also provides further strengthening of the frame. The camming bar provides an arcuately bent upper end 146 which is adapted to be slidably engaged by the flight members as they begin to traverse the outer run of the chains so as to insure outward swinging of the flight members in non-interfering relation with the inner runs of the chains.

Located adjacent to the top side 25 of the frame substantially intermediate the opposite ends 27 and 28 thereof is a tray pick-off mechanism, generally indicated by the reference numeral 150. The tray pickoff mechanism provides a guide frame 152 having a pair of opposite front and rear elongated substantially rectangular panels 153 and 154, respectively, adjacent to the front and back sides 22 and 23 of the frame 10. The panels are interconnected by opposite side guide tracks 156 constructed of a pair of upper and lower angle irons 157 and 158, respectively, providing spaced, substantially parallel facing rails 160 and 162, respectively.

The guide frame 152 of the tray pick -off mechanism 150 is supported in depending relation from the upper connector beams 32 at the front and back sides 22 and 23 of the frame 10 by a plurality of substantially upright hanger angle irons 165 upwardly extended from the four corners of the guide frame. Each of the hangers has an elongated slot 166 therein through which is extended an elongated bolt and nut assembly 167 for extension through the associated connector beam 32. Accordingly, the guide frame'l52 is vertically adjustable with respect to the frame and to the stack of trays therein.

A wheeled dolly 170 is mounted for reciprocation within the guide frame 152 which has a substantially rectangularbottom plate 172, upturned side walls 174, and a front wall 175 adjacent to the front side 22 of the frame 10. A pair of gro oved wheels 177 are mounted on the side walls 174 in rolling engagement between the upper and lower rails 160 and 162 of the guide track 156 of the frame 152. A pair of laterally spaced tray pick-off arms 180 are mounted in depending relation from the front side 175 of the dolly which individually include a wedge-shaped tray pick-off finger 182 disposed in facing relation to the stack of trays within the frame 10. An hydraulic jack 185 is mounted within the guide frame 152 for reciprocating the dolly 170 along the guide track 156 of the guide frame. The hydraulic jack provides a cylinder end 187 which is connected to an angle iron 188 secured to the inner face of the rear panel 154 of the guide frame and an opposite rod end 190 secured to a bracket 191 extended rearwardly from the front side 175 of the dolly.

A control mechanism 195 for controlling the sequence of operation of the stack elevating conveyor 50 and the tray pick-off mechanism 150 is disposed in the frame 10 below the guide frame 152. An elongated mounting bar 197 is extended substantially centrally between the front and rear panels 153 and 154 on which is mounted a solenoid valve 198 having a depending trip lever 200 extended downwardly therefrom which is provided with a tray engaging foot 202. The solenoid is connected to a control system, not shown, for the hydraulic motor for driving the stack elevating conveyors 50 and the hydraulic jack for reciprocating the dolly and tray pick-off arms 180.

A tray separating mechanism 205 is mounted on the back side 23 of the frame 10 adjacent to a tray discharge station generally indicated by the reference numeral 207. The tray separating mechanism provides a pair of spaced fingers 208 which are slidably reciprocably mounted within a pair of elongated substantially rectangular sleeves 210. Each of the fingers has a tapered forward end 211 and an opposite outer control end 212 outwardly extended from the sleeve. Each sleeve is mounted in a substantially horizontal position on a vertically upstanding adjustable arm 214 in order to position the sleeve to permit the forward tapered end of the finger to be extended between the uppermost tray in the stack and the tray beneath it. The adjusting arm is mounted on a bracket 218 outwardly extended from the intermediate connector beam 35 of the frame 10-which, at its outer end, mounts a substantially upright bearing and pillow block mounting pad 219..

An elongated control shaft 220 is rotatably extended through a pair of spaced bearing and pillow block assemblies 222 individually mounted on the pads 219 which has a pair of levers 223 upwardly extended from the opposite ends of the shaft. Each of the levers has a link 224 connecting the upper end thereof with the outer control end 212 of each of the fingers. A lower control lever 226 is downwardly extended from one end of the control shaft for pivotal connection to the rod end 227 of an hydraulic jack 228. The jack-includes a cylinder end 230 which is pivotally connected to an elongated sleeve 232 secured in elevationally adjusted position on an elongated substantially upright support rod 235 extended in interconnecting relation between the intermediate and lower connector beams 35 and 34, respectively, of the frame.

The tray discharge station 207 at the back side 23 of the frame 10 includes a tray propelling system, generally indicated by the reference numeral 240 for completing the discharge of the trays one at a time from the frame onto a tray receiving conveyor fragmentarily indicated at 242 in FIG. 7. Such system includes an elongated shaft 245 journaled at its opposite ends in bearing and pillow block assemblies 247 individually mounted on the rear faces of the corner posts 30. A plurality of tray engaging rollers including a centrally disposed intermediate roller 250 and a pair of opposite end rollers 252 are mounted on the shaft with the end rollers including annular outer flanges 253 for maintainingthe discharged trays laterally centered upon the rollers accurately to guide them onto the tray discharge conveyor 242. The rollers are continually rotated by an hydraulic drive motor 255 mounted one one of the corner posts 30 through a sprocket and chain drive arrangement generally indicated by the reference numeral 257.

OPERATION The operation of the described embodiment of the subject invention is believed to be clearly apparent and is briefly summarized at this point. Prior to initiation of the unstacking operation, a stack of the trays 20 is rolled into the frame 10 of the unstacking machine of the present invention upon the railway car 16. During such entry, the stack of trays is automatically centered with respect to the frame by engagement of the sides of the trays with the rollers 40 at each side of the opening through the front side 22 of the frame. It will be noted that the trays are substantially wider than the flat bed 17 on the railway car in order to overhang the bed to permit unrestricted engagement of the lowermost tray by the flight members 110 of the stack elevating conveyors 50.

Upon energization of the hydraulic motor 90, the inner runs 53 of both conveyors are traveled upwardly by virtue of the cross chain drive of the chains 87 and 88 between the upper outer drive transfer sprockets 68 at the front and back sides of the frame. During such movement, the lowermost flight member 110 is moved from its downwardly depending position of FIG. inwardly upwardly to a position disposed beneath the lowermost tray of the stack, as shown in FIG. 1. Continued movement. of the conveyors raises the entire stack of trays upwardly from the flat bed 17 of the railway car 16 so that the uppermost tray in the stack is elevated to the position shown in FIG. 7. In such position, the lower edge of the uppermost tray is substantially aligned with the finger 182 of the pick-off arms 180 and with the fingers 208 of the tray separating mechanism 205.

Also during the above described elevational movement of the stack of trays, the uppermost tray engages the trip lever 200 on the solenoid valve 198 which is raised to its dashed line position, as shown in FIG. '7, temporarily through the control system, not shown, to terminate operation of the hydraulic motor 90 and movement of the stack elevating conveyors 50. Such actuation of the solenoid valve is further effective through the control system to energize the cylinder end 230 of the hydraulic jack 228 to cause the fingers 208 to be extended from their respective sleeves 210 for insertion between the uppermost tray and the tray beneath it to insure unrestricted separation of such trays.

Immediately after such operation 'of the tray separating fingers 208, the rod end of the hydraulic jack 185 is energized to retract the rod end 190 therein to travel the dolly 170 through the guide track 156 toward the back side 23 of the frame 10. Such movement causes the fingers 182 of the pick-off arms 180 to engage the uppermost tray in the stack and to shove it laterally outwardly through the discharge station 207 and onto the tray propelling rollers 250 and 252. Such rollers are continuously rotated throughout the entire unstacking operation by the hydraulic motor 255 which completes the discharge of the trays from the frame of the unstacking machine one at a time with no manual handling required. The end flanges on the end rollers 252 assure rectilinear travel of the trays onto the tray receiving conveyor 242.

After such removal of the uppermost tray is completed, the finger 200 on the solenoid valve 198 is spring-returned downwardly to its full line position shown in FIG. 7 and the fingers 208 of the tray separating mechanism and fingers 182 of the tray pick-off mechanism are returned to their original retracted positions. The return of the fingers of the solenoid valve re-energizes the motor to the stack elevating conveyors 50 so that the stack is again raised to position the uppermost tray adjacent to the tray discharge station in the frame. The same procedure is repeated for each succeeding tray to be raised with the uppermost tray being picked off and discharged outwardly through the discharge station with each sequence of operation. After the last tray in the stack has been discharged, the conveyors 50 are further rotated and stopped by a limit switch or the like, not shown, in the control system so that the previously unused flight member in the preceding sequence of operation is now positioned in depending relation adjacent to the lower sprocket S8 in position for receiving a subsequent stack of trays into the frame and to lift and discharge them one at a time through the upper discharge station. Even though the hydraulic control system for the hydraulic jacks 18S and 228 is not shown, it can be readily understood that the above described sequential action between the tray separating mechanism 205 and the tray pick-off mechanism is obtained by virtue of placing the hydraulic control valves closer to the tray separating mechanism to in sure its operation an instant before actuation of the-tray pick-off mechanism. It is to be understood that where the trays 20 of the stack adhere with sufficient tenacity, due to the presence of tacky residue, additional pairs of spaced fingers 208 can be employed concurrently with the fingers 208 mounted adjacent to the tray discharge station 207 for achieving a rapid and efficient separation of the trays as the fingers are inserted therebetween.

In view of the foregoing, it is readily apparent that the structure of the present invention provides an improved unstacking machine for a plurality of elevationally stacked trays or the like which is substantially automatic requiring a minimum of manual attention and which substantially eliminates manual handling of the trays during the unstacking operation. The unstacking machine is capable of receiving an entire stack of raisin trays as they are conventionally disposed during the drying process and efficiently removes the trays therefrom one at a time onto the tray receiving conveyor for further processing of the contents of the trays without any manual handling or guiding of the trays onto such conveyor.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An unstacking machine for trays or the like disposed in elevationally stacked relation comprising a frame adapted to receive such a stack of trays therein, powered tray pick-off means mounted on the frame for reciprocal movement successively to engage the uppermost tray in the stack and to remove it laterally from the stack, tray separating means including a plurality of tapered fingers supported for lateral reciprocation and adapted to be inserted between said uppermost tray and the tray immediately beneath the uppermost tray for separating the trays prior to the initiation of movement of said pick-off means for removing the uppermost tray, and powered stack elevating means for advancing the stack upwardly through successive increments of travel to position each succeeding uppermost tray in the path of movement of said pick-off means for removing one tray at a time from the stack.

2. The unstacking machine of claim 1 including automatic control means having a trip member on the frame engageable by said uppermost tray each time the stack is elevated to initiate said reciprocal movement of said pick-off means laterally to remove the uppermost tray from the stack.

3. The unstacking machine of claim 2 in which said frame includes predetermined opposite top and bottom sides, a relatively open front stack receiving side, an opposite back side providing a tray discharging station adjacent to said top side of the frame,-and opposite ends interconnecting said sides.

4. The unstacking machine of claim 3 in which said tray discharging station includes a plurality of continuously rotating powered rollers on the frame in position to be engaged by said uppermost tray during said movement of the pick-off means to propel said tray outwardly from the frame.

5. The unstacking machine of claim 4 in which said stack elevating means includes a pair of endless conveyors individually mounted in spaced substantially parallel relation on said opposite ends of the frame for circuitous movement between said bottom and top sides of the frame.

6. The unstacking machine of claim 5, in which said conveyors individually provide an inner stack raising run and an opposite outer return run, and a pair of stack engaging flight members mounted in spaced relation upon the conveyor for alternate traversement of said inner run individually to raise successive stacks of trays in the frame.

7. The unstacking machine of claim 6 in which each of said flight members is pivotally mounted in depending relation from said conveyor, and an elongated substantially upright cam bar is disposed in outwardly spaced relation from each end of the frame for sliding engagement by said flight members as they traverse said outer return run of the conveyor so as to swing the flight members outwardlyfor unrestricted movement past said ends of the frame.

8. The unstacking machine of claim 7 including inner guide means on the frame for slidably receiving said inner run of the conveyor to constrain it to a substantially upright path of travel, and outer guide means slidably receiving said outer return run of the conveyor disposed in outwardly spaced relation to said end of the frame for holding said outer run and said flight members in outwardly spaced non-interfering relation to said end of the frame.

9. An unstacking machine for handling a plurality of trays or the like comprising a frame having opposite top and bottom sides, a relatively open front side adapted to receive such a stack of trays therethrough for deposit within the frame, an opposite back side providing a tray discharging station adjacent to said top side, and opposite ends interconnecting said sides; a powered tray pick-off mechanism mounted on the top side of the frame for reciprocal movement along a path above the stack and having depending tray engaging means thereon for removing the uppermost tray laterally from the stack; a plurality of elongated wedge shaped fingers mounted for reciprocation toward and from the stack for insertion between said uppermost tray and the tray immediately beneath it; and a pair of powered endless conveyors individually mounted on said opposite ends of the frame having flight members extendible beneath the stack of trays in supporting relation thereto upwardly to advance the stack through successive increments of travel to position each succeeding uppermost tray in the path of movement of said tray engaging means on the tray pick-off mechanism for lateral discharge of the uppermost tray through said tray discharging station.

10. The unstacking machine of claim 9 including a plurality of continuously rotating powered rollers on the frame adjacent to said tray discharging station and 'having upper peripheries engageable by said uppermost tray upon said movement of the tray pick-off mechanism to propel said tray outwardly from the frame.

11. The unstacking machine of claim 10 including automatic control means having a trip member on the top side of the frame engageable by said uppermost tray during each elevational increment of travel of the stack by said stack elevating conveyors to initiate said reciprocal movement of said finger of the tray separating mechanism for insertion between the uppermost tray and the tray beneath it and said reciprocal movement of the tray pick-off mechanism laterally to remove the uppermost tray from the stack.

12. The unstacking machine of claim 11 in which said conveyors individually provide an inner stack raising run and an opposite outer return run, and a pair of stack engaging flight members mounted in spaced relation upon the conveyor for alternate traversement of said inner run individually to raise successive stacks of trays in the frame.

13. The unstacking machine of claim 12 in which said flight member is pivotally mounted in depending relation from said conveyor, and an elongated substantially upright cam bar is disposed in outwardly spaced relation from each end of the frame for sliding engagement by said flight members as they traverse said outer return run of the conveyor so as to swing the flight members outwardly for unrestricted movement past said ends of the frame.

14. The unstacking machine of claim 12 including inner guide means on the frame for slidably receiving said inner run of the conveyor to constrain it to a substantially upright path of travel, and outer guide means slidably receiving said outer return run of the conveyor disposed in outwardly spaced relation to said end of the frame for holding said outer run and said flight members in outwardly spaced non-interfering relation to said end of the frame.

15. An unstacking machine for trays or the like disposed in elevationally stacked relation comprising a frame including predetermined opposite top and bottom sides, a relatively open front stack receiving side, an opposite back side providing a tray discharging station adjacent to said top side of the frame adapted to receive such a stack of trays therein, powered tray pick-off means mounted on the frame for reciprocal movement successively to engage the uppermost tray in the stack and to remove it laterally substantially horizontally from the stack, tray separating means mounted for reciprocal movement on the frame at said tray discharging station for insertion between said uppermost tray and the tray beneath said uppermost tray just prior to the initiation of said movement of said pick-off means to remove said uppermost tray, a plurality of continuously rotating powered rollers supported on the frame at said discharge station in position to be engaged by said uppermost tray during said movement of the pick-off means to propel said tray outwardly from the frame, and powered stack elevating means on the frame being operative to advance the stack upwardly through successive increments of travel to position each succeeding uppermost tray in the path of movement of said pick-off means for removing one tray ata time from the stack.

16. An unstacking machine for handling a plurality of trays or the like comprising a frame having opposite top and bottom sides, a relatively open front side adapted to receive such a stack of trays therethrough for deposit within the frame, an opposite back side providing a tray discharging station adjacent to said top side, and opposite ends interconnecting said sides; a

powered tray pick-off mechanism mounted on the top side of the frame for reciprocal movement along a path above the stack and having depending tray engaging means thereon for removing the uppermost tray laterally from the stack; a tray separating mechanism mounted on the back side of the frame adjacent to said tray discharging station and having an elongated wedge shape finger mounted for reciprocation toward and from the stack of trays for insertion between said uppermost tray and the tray beneath it; a pair of powered endless conveyors individually mounted on said opposite ends of the frame having flight members extendible beneath the stack of trays in supporting relation thereto to advance the stack upwardly through successive increments of travel to position each succeeding uppermost tray in the path of movement of said tray engaging means on the tray pick-off mechanism for lateral discharge of the uppermost tray through said tray discharging station; and a plurality'of continuously rotating powered rollers on the frame adjacent to said tray discharging station and having upper peripheries engageable by said uppermost tray upon said movement of the tray pick-off mechanism to propel said tray outwardly from the frame. 

1. An unstacking machine for trays or the like disposed in elevationally stacked relation comprising a frame adapted to receive such a stack of trays therein, powered tray pick-off means mounted on the frame for reciprocal movement successively to engage the uppermost tray in the stack and to remove it laterally from the stack, tray separating means including a plurality of tapered fingers supported for lateral reciprocation and adapted to be inserted between said uppermost tray and the tray immediately beneath the uppermost tray for separating the trays prior to the initiation of movement of said pick-off means for removing the uppermost tray, and powered stack elevating means for advancing the stack upwardly through successive increments of travel to position each succeeding uppermost tray in the path of movement of said pick-off means for removing one tray at a time from the stack.
 2. The unstacking machine of claim 1 including automatic control means having a trip member on the frame engageable by said uppermost tray each time the stack is elevated to initiate said reciprocal movement of said pick-off means laterally to remove the uppermost tray from the stack.
 3. The unstacking machine of claim 2 in which said frame includes predetermined opposite top and bottom sides, a relatively open front stack receiving side, an opposite back side providing a tray discharging station adjacent to said top side of the frame, and opposite ends interconnecting said sides.
 4. The unstacking machine of claim 3 in which said tray discharging station includes a plurality of continuously rotating powered rollers on the frame in position to be engaged by said uppermost tray during said movement of the pick-off means to propel said tray outwardly from the frame.
 5. The unstacking machine of claim 4 in which said stack elevating means includes a pair of endless conveyors individually mounted in spaced substantially parallel relation on said opposite ends of the frame for circuitous movement between said bottom and top sides of the frame.
 6. The unstacking machine of claim 5, in which said conveyors individually provide an inner stack raising run and an opposite outer return run, and a pair of stack engaging flight members mounted in spaced relation upon the conveyor for alternate traversement of said inner run individually to raise successive stacks of trays in the frame.
 7. The unstacking machine of claim 6 in which each of said flight members is pivotally mounted in depending relation from said conveyor, and an elongated substantially upright cam bar is disposed in outwardly spaced relation from each end of the frame for sliding engagement by said flight members as they traverse said outer return run of the conveyor so as to swing the flight members outwardly for unrestricted movement past said ends of the frame.
 8. The unstacking machine of claim 7 including inner guide means on the frame for slidably receiving said inner run of the conveyor to constrain it to a substantially upright path of travel, and outer guide means slidably receiving said outer return run of the conveyor disposed in outwardly spaced relation to said end of the frame for holding said outer run and said flight members in outwardly spaced non-interfering relation to said end of the frame.
 9. An unstacking machine for handling a plurality of trays or the like comprising a frame having opposite top and bottom sides, a relatively open front side adapted to receive such a stack of trays therethrough for deposit within the frame, an opposite back side providing a tray discharging station adjacent to said top side, and opposite ends interconnecting said sides; a powered tray pick-off mechanism mounted on the top side of the frame for reciprocal movement along a path above the stack and having depending tray engaging means thereon for removing the uppermost tray laterally from the stack; a plurality of elongated wedge shaped fingers mounted for reciprocation toward and from the stack for insertion between said uppermost tray and the tray immediately beneath it; and a pair of powered endless conveyors individually mounted on said opposite ends of the frame having flight members extendible beneath the stack of trays in supporting relation thereto upwardly to advance the stack through successive increments of travel to position each succeeding uppermost tray in the path of movement of said tray engaging means on the tray pick-off mechanism for lateral discharge of the uppermost tray through said tray discharging station.
 10. The unstacking machine of claim 9 including a plurality of continuously rotating powered rollers on the frame adjacent to said tray discharging station and having upper peripheries engageable by said uppermost tray upon said movement of the tray pick-off mechanism to propel said tray outwardly from the frame.
 11. The unstacking machine of claim 10 including automatic control means having a trip member on the top side of the frame engageable by said uppermost tray during each elevational increment of travel of the stack by said stack elevating conveyors to initiate said reciprocal movement of said finger of the tray separating mechanism for insertion between the uppermost tray and the tray beneatH it and said reciprocal movement of the tray pick-off mechanism laterally to remove the uppermost tray from the stack.
 12. The unstacking machine of claim 11 in which said conveyors individually provide an inner stack raising run and an opposite outer return run, and a pair of stack engaging flight members mounted in spaced relation upon the conveyor for alternate traversement of said inner run individually to raise successive stacks of trays in the frame.
 13. The unstacking machine of claim 12 in which said flight member is pivotally mounted in depending relation from said conveyor, and an elongated substantially upright cam bar is disposed in outwardly spaced relation from each end of the frame for sliding engagement by said flight members as they traverse said outer return run of the conveyor so as to swing the flight members outwardly for unrestricted movement past said ends of the frame.
 14. The unstacking machine of claim 12 including inner guide means on the frame for slidably receiving said inner run of the conveyor to constrain it to a substantially upright path of travel, and outer guide means slidably receiving said outer return run of the conveyor disposed in outwardly spaced relation to said end of the frame for holding said outer run and said flight members in outwardly spaced non-interfering relation to said end of the frame.
 15. An unstacking machine for trays or the like disposed in elevationally stacked relation comprising a frame including predetermined opposite top and bottom sides, a relatively open front stack receiving side, an opposite back side providing a tray discharging station adjacent to said top side of the frame adapted to receive such a stack of trays therein, powered tray pick-off means mounted on the frame for reciprocal movement successively to engage the uppermost tray in the stack and to remove it laterally substantially horizontally from the stack, tray separating means mounted for reciprocal movement on the frame at said tray discharging station for insertion between said uppermost tray and the tray beneath said uppermost tray just prior to the initiation of said movement of said pick-off means to remove said uppermost tray, a plurality of continuously rotating powered rollers supported on the frame at said discharge station in position to be engaged by said uppermost tray during said movement of the pick-off means to propel said tray outwardly from the frame, and powered stack elevating means on the frame being operative to advance the stack upwardly through successive increments of travel to position each succeeding uppermost tray in the path of movement of said pick-off means for removing one tray at a time from the stack.
 16. An unstacking machine for handling a plurality of trays or the like comprising a frame having opposite top and bottom sides, a relatively open front side adapted to receive such a stack of trays therethrough for deposit within the frame, an opposite back side providing a tray discharging station adjacent to said top side, and opposite ends interconnecting said sides; a powered tray pick-off mechanism mounted on the top side of the frame for reciprocal movement along a path above the stack and having depending tray engaging means thereon for removing the uppermost tray laterally from the stack; a tray separating mechanism mounted on the back side of the frame adjacent to said tray discharging station and having an elongated wedge shape finger mounted for reciprocation toward and from the stack of trays for insertion between said uppermost tray and the tray beneath it; a pair of powered endless conveyors individually mounted on said opposite ends of the frame having flight members extendible beneath the stack of trays in supporting relation thereto to advance the stack upwardly through successive increments of travel to position each succeeding uppermost tray in the path of movement of said tray engaging means on the tray pick-off mechanism for lateral discharge of the uppermost tray through said tray dischargIng station; and a plurality of continuously rotating powered rollers on the frame adjacent to said tray discharging station and having upper peripheries engageable by said uppermost tray upon said movement of the tray pick-off mechanism to propel said tray outwardly from the frame. 